Sportswear such as mountain climbing wear is generally required to have mobility or lightness upon wearing, as well as excellent moisture permeability and the like. Moisture permeability is an important property for suppressing the unpleasant feeling due to, for example, the sultriness caused by moisture generated from the body, such as sweat, staying within the clothes.
As for the clothes having excellent moisture permeability, there is known, for example, a heat-retaining, moisture-permeable, waterproof cloth prepared by bonding a film containing a water-swellable, moisture-permeable urethane resin and heat reflective fine metal fragments, and a fiber cloth, using a reactive hot melt adhesive of a moisture-curable urethane resin (see, for example, Patent Document 1).
However, the reactive hot melt adhesive used in the Patent Document 1 does not have moisture permeability per se. For that reason, when this adhesive is used in the adhesion of moisture-permeable base materials, the adhesive seals the moisture permeating pores present in the moisture-permeable base materials, and as a result, the excellent moisture permeability possessed by the base materials may be markedly decreased.
Furthermore, since the reactive hot melt adhesive which is specifically exemplified in the Patent Document 1 may form an adhesive layer having relatively high hardness, when the adhesive is used in the adhesion of base materials having a soft and pliable texture, the soft and pliable texture of the base materials is markedly impaired, and as a result, the wear comfort of clothes made from the base materials may be decreased.
As the method of preventing significant decreases in the moisture permeability or pliability of a base material, a method is known for adhering a base material according to an intermittent application method (dot bonding method) in which an adhesive is applied on the base material in a dotted pattern, as described in the Patent Document 1.
However, in a laminate having a plurality of base materials laminated according to the intermittent application method, because the contact points between the base materials and the adhesive are usually very small, sufficient ordinary state adhesive strength may not maintained, and delamination of the base materials may occur. In particular, when clothes and the like produced by the above-described method are laundered in water, the adhesive strength of the adhesive is markedly decreased under the influence of water or detergent, and as a result, delamination of base materials may occur.
On the other hand, the delamination of base materials can be suppressed to some extent, for example, by increasing the amount of adhesive applied, or the like. However, since the moisture permeability or pliability possessed by a base material is decreased as an increase in the amount of application of the adhesive, it was difficult to elicit a good balance between excellent adhesive strength, moisture permeability and pliability in such methods.
As described above, under the current circumstances, a moisture-curable polyurethane hot melt adhesive, which would not cause a significant decrease in the excellent moisture permeability or pliability of base materials and has all of excellent ordinary state adhesive strength, water-resistant adhesive strength, moisture permeability and pliability, has not yet been found.
However, concerning the aforementioned base material which has excellent moisture permeability and can be used in the manufacture of clothes such as sportswear, it is known that films formed from porous polytetrafluoroethylene or urethane resins can also be used, in addition to fiber cloths which have porous relatively between fibers.
These moisture-permeable films are usually formed by flow casting a solvent-based or aqueous resin solution on a releasable base material, and then volatilizing the solvent.
However, the production method of films as described above has been regarded as a problem in recent years, in view of requiring enormous energy upon volatilizing the solvent.
Therefore, there is a demand for the development of a moisture-permeable film which can be produced using largely reduced energy consumption, and has excellent moisture permeability and pliability.
Patent Document 1: Japanese Patent Application Laid-Open No. 2002-370335